氮化铝粉末制备与应用研究进展

氮化铝陶瓷因具有高导热率、各种电性能优越、机械性能好、良好的化学稳定性等优点,可作为封装散热基板和电子元件制造的理想材料.而氮化铝陶瓷的优良性能基于其粉体的高品质,要想获得性能优良氮化铝陶瓷,关键是要制备高质量的氮化铝粉体.随着5G时代的到来,氮化铝作为最理想的基片材料,如何制备高质量高性能的氮化铝粉末成为先进材料方向...     

氮化铝粉体工程的研究进展

电子技术微型化、轻型化、高集成和大功率的发展,对基板和封装材料提出更高要求。氮化铝陶瓷具有高导热性、绝缘性、热膨胀系数与半导体硅相近、机械强度高、化学稳定性好、无毒无害等优良特性,是理想的基板材料之一,具有很好的发展前景。高质量氮化铝粉体是制备高性能氮化铝陶瓷的关键。本文分别归纳介绍了微米/纳米氮化铝合成的新技术、新方法及其研究进展,并展望了氮化铝粉体合成的发展趋势。     

氮化铝粉体工程的研究进展

电子技术微型化、轻型化、高集成和大功率的发展,对基板和封装材料提出更高要求。氮化铝陶瓷具有高导热性、绝缘性、热膨胀系数与半导体硅相近、机械强度高、化学稳定性好、无毒无害等优良特性,是理想的基板材料之一,具有很好的发展前景。高质量氮化铝粉体是制备高性能氮化铝陶瓷的关键。本文分别归纳介绍了微米/纳米氮化铝合成的新技术、新方法及其研究进展,并展望了氮化铝粉体合成的发展趋势。     

氮化铝陶瓷粉体制备方法研究进展及展望

氮化铝具有良好的热学、电学和机械等性能,是理想的电子封装材料和高性能陶瓷基板材料.本文论述了目前国内外氮化铝陶瓷粉体的主要制备方法及其特点,分析了氮化铝粉体制备的主要影响因素,阐述了主要解决措施,展望了氮化铝陶瓷粉体制备技术研究发展的方向.     

亚微米氮化铝粉体改性微米氮化铝陶瓷的研究

以低温燃烧工艺结合碳热还原法制备获得的粒径30~180nm氮化铝粉体作为添加剂,探讨了不同量和不同粒径亚微米氮化铝粉体对微米氮化铝陶瓷烧结性能和热传导性能的影响规律。结果发现,在微米氮化铝粉体中添加适量的亚微米氮化铝粉体,可在一定程度上促进氮化铝陶瓷的烧结,在1800℃即能实现致密化,并提高氮化铝陶瓷的热导率;亚微米氮化铝粉体的添加量以1.5wt%、粒径以120~150nm为最佳。但亚微米氮化铝粉体对微米氮化铝陶瓷的改性作用有限,1800℃烧结得到陶瓷的极限密度仅为3.12g·cm-3,低于氮化铝陶瓷的理论密度3.26g·cm-3,且陶瓷内部存在少量的气孔,其热导率为64.87W/(m·K)。     

氮化铝陶瓷的研制及应用

氮化铝 (AlN)因具有高热导率、低介电常数、与硅相匹配的热膨胀系数及其他优良的物理特性 ,在新材料领域越来越引起人们的关注。此文主要介绍并分析了AlN粉体合成、烧结、性能结构、AlN陶瓷的应用与前景     

氮化铝陶瓷的制备及其在复合材料中的应用研究

氮化铝(AlN)陶瓷是一种性能优良的高技术陶瓷.本文概述了AlN陶瓷粉体的合成、成形、烧结的制备过程及其在复合材料中的应用研究,指出要更多地开展AlN复合材料及其在复合材料中应用的研究工作,以满足科技发展对材料提出的更高要求.     

高热导电绝缘氮化铝陶瓷在宇航器件中的应用：概述、挑战和展望

氮化铝(AlN)陶瓷具有高热导、高电阻、低介电损耗、低膨胀以及良好的力学性能等特性,可用作高性能导热基板和陶瓷封装材料。本工作评述了AlN粉体及陶瓷的制备技术、性能特性及宇航应用等方面的研究状况,讨论了宇航应用的挑战和启发,进一步对其在空间技术中的应用潜力进行展望。     

氮化铝陶瓷的研制及应用

氮化铝（AIN）因具有高热导率、低介电常数、与硅相匹配的热膨胀系数及其他优良的物理特性，在新材料领域越来越引起人们的关注。此文主要介绍产分析了AIN粉体合成、烧结、性能结构、AIN陶瓷的应用与前景。     

高热导率氮化铝陶瓷研究进展

氮化铝(AIN)陶瓷具有热导率高、热膨胀系数低、电阻率高等特性以及良好的力学性能,被认为是新一代高性能陶瓷基片和封装的首选材料.本文简要介绍了氮化铝陶瓷的基本特性,重点总结了氮化铝陶瓷的国内外研究现状及其制备工艺,并列举了一些氮化铝陶瓷的应用实例.     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

用两个形状指数表征粉煤灰颗粒形貌的研究

引用两个形状指数表征颗粒形状的概念,即先将颗粒形状近似为椭圆,再将椭圆图像分离:以圆为基准的颗粒宏观形状指数δ;以光滑椭圆为基准的颗粒轮廓凹凸度,即微观形状指数ζ。分析和发展了近似椭圆模型。并运用图像分析仪对粉煤灰、水泥样品进行实验。结果表明,粉煤灰颗粒的两个形状指数δ和ζ都大于水泥颗粒。证明粉煤灰颗粒的球形度、表面光滑度优于水泥,而且,随着粒径增大,δ和ζ呈下降趋势,表明磨制颗粒越粗。(?)粒形状越不规则。文中还运用近似椭圆模型再现了颗粒的模拟图像。     

典型煤碳燃烧特性研究和数值模拟

本文以三种典型煤的碳燃烧为研究对象，分别采用简单一维沉降燃烧方式和等温加热燃烧方式，实验研究了煤在快速加热条件下，其碳的初期和中，后期燃烧过程。以实验为基础，建立了煤的碳燃烧模型，变工况数值模拟了煤的碳燃烧过程，揭示了煤不同条件下的单颗粒碳燃烧特性。